Multiscale reservoir heterogeneity in fracture-controlled dolomites, Albion-Scipio and Stoney Point fields, Michigan

Conference · Fri Sep 01 04:00:00 EDT 1989 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:5631464

Hurley, N F; Swager, D R ^[1]

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1. Marathon Oil Co., Littleton, CO (USA)

Albion-Scipio and Stoney Point fields, Michigan, have produced more than 125 million bbl (20 million m{sup 3}) of oil from fracture-controlled, Middle Ordovician dolomites. Albion-Scipio is 30 mi (50 km) long and Stoney Point is 10 mi (16 km) long; both fields are about 0.5 mi (0.8 km) wide. Heterogeneity exists at many scales, ranging from megascopic (field scale) to microscopic (pore scale). Structurally, the fields are synclinal sags that lie on a regional, northeast-dipping homoclinal surface. Local structure consists of en echelon troughs that are generally 1 mi (1.609 km) long and have vertical relief of 30 to 60 ft (10-20 m). The en echelon pattern suggests left-lateral strike-slip motion on a reactivated basement fault. At a field scale, then, reservoirs contain synclinal compartments with distinctive production and pressure histories. On an interwell scale, geologic and geochemical studies suggest that porosity development is genetically related to near-vertical natural fractures. Dolomitized rocks are apparently broken into narrow (few feet or meters), elongate reservoir compartments oriented parallel to local structure. Porous compartments are separated from each other by blocks of nonreservoir dolomite. Lateral boreholes suggest that porous compartments have an average spacing of 45 ft (15 m) or less. Pores consist mainly of vugs, fractures, caverns, and some intercrystalline voids. Although core porosities vary from 0 to 12%, permeabilities range over six orders of magnitude (0.01 to 8,000 md). Thus, even on a microscopic scale, significant reservoir heterogeneity exists.

• OSTI ID: 5631464
• Report Number(s): CONF-8910195--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 73:9
• Country of Publication: United States
• Language: English

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